Continuous grease manufacture



Feb. 20, 1951 L. B. STEVENS CONTINUOUS GREASE MANUFACTURE Filed Dec. 14, 1946 mn@ Q S n VY mw /mm Te. N DOA m6 #am 2, B k /f 1 Z wmwwq www @m2 u MJY 6( 53m? u a mw L l @S Mw /E Si@ 52.5%

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Patented Feb. 20, 1951 UNETED STATES PATENT OFFICE CONTINUOUS GREASE MANUFACTURE Langley B. Stevens, Wilmington, Del., assigner to The Pure Oil Company, Chicago, Ill., a. corporation of Ohio Application December 14, 1946, Serial No. 716,413

3 Claims.

ratus have been fairly satisfactory, for the prepa' ration of some types of grease, as for example, the preparation of aluminum soap greases, none of the methods and apparatus are very satisfactory for manufacture of other types of greases, such as sodium soap, calcium soap, and sodalime greases.

One of the objects of my invention is to provide a method for continuous or semi-continuous manufacture of greases. f

Another object of my invention is to provide apparatus for continuous or semi-continuous manufacture of greases.

A still further object of the invention is to provide apparatus capable of manufacturing various types of greases in a continuous or semicontinuous operation.

Other objects of the invention will become apparent from the following description of which the drawing is a diagrammatic, elevational View of apparatus in accordance with the invention.

Referring to the drawing, the numeral I indicates a line through which soap, mineral oil and Various additives may be fed in proportioned amounts to either slurry tank 3 through line 5 controlled by valve 6, or slurryl tank 'I through line 9 controlled by valve I0. Connected to the bottom of the slurry tank 3 is a line I I controlled by Valve I3. Connected to the bottom of slurry tank 1 is a line I5 controlled by valve I1. The lines II and I are connected through line I9 to the inlet of disperser or homogenizer 2 I. Any suitable apparatus capable of dispersing additive in the oil may be used as a disperser or homogenizer. We have found that a Cornell mixer or a Marco Kombinator is highly satisfactory for this purpose. The Kombinator is described in a brochure entitled The Flow-Master Line of Processing Equipment, Catalog #10, issued by the Marco Co., Inc., 3rd and Church Sts., Wilmington, 50, Delaware.

The outlet of disperser or homogenizerll is connected through line 23 and lines 25 and 21 to 4 the top of slurry tanks 3 and 1, respectively. Lines Z5 and 21 are controlled by valves 29 and 3|, respectively. By means of the lines and valves just described, a mixture of soap, oil and additives can be circulated from either slurry tank 3 or slurry tank 1 through the homogenizer 2| in order to prepare a good suspension of the soap and additives in the oil.

Connected to the bottom of slurry tanks 3 and 1 are lines 33 and 35, respectively, controlled by valves 31 and 39. Lines 33 and 35 are connected through line 4I controlled by valve 42 to the inlet side of the'pump 43. The outlet side of pump 43 is connected by line 45 to the inlet of f an eiiicient heat exchanger 41 which is designed to heat the suspension of soap and additive in oil to the desired temperature while continuously passing therethrough and while maintaining the soap and additive in suspension in the oil. An efficient heat exchanger for this purpose is the Votator manufactured by the Girdler Corporation, the operation of which is described in Industrial & Engineering Chemistry, vol. 36, No. 6, pages 522-528.

The outlet of the heat exchanger 41 is connected by a line 49 controlled by valve 5l to the inlet of a second homogenizer 53 such as a Kombinator or Cornell mixer, Where complete dispersion of the soap in the oil is obtained by means of the extremely high conditions of shear developed in the homogenizer. From the outlet of the homogenizer or disperser 53 the grease passes through line 55 to a heat exchanger 51 such as a cooling Votator, where the grease is cooled down to a desired temperature for further processing. Heat exchanger 41 is directly connected to cooler 51 by by-pass line 55 controlled by valve 55. The outlet of the heat exchanger 51 is connected by means of line 55, controlled by valve GI, to the inlet of a third disperser or homogenizer B3 which may also be a Cornell mixer or a Kombinator and is also connected to valve-controlled Withdrawal line S4. A conduit 55 is connected to the outlet of the homogenizer 63 through which the nished grease is withdrawn for packaging.

A line 61 connects the outlet of the heat exchanger 51 through line 69 controlled by the valve 1I to the inlet of pump 43. The outlet of heat exchanger 51 is also connected by means of line 61 and line 13, controlled by valve 15, to the upper portion of time lag tank 11. The bottom of the time lag tank 11 is connected by line 19 to the inlet sideof pump 8|. The outlet side of pump 8l is connected through line 83, controlled by valve and line 81 to the inlet side of disperser or homogenizer 53.

The operation of the apparatus just described will depend to some extent on the type of grease which it is desired to manufacture.f ln starting up the apparatus, mineral oil of the proper physical and chemical characteristics for making grease is charged into either slurry tank 3 or 1. The required amount of soap and such additives as it is desired to add are also charged into the slurry tank.

In making the grease, sodium, calcium, aluminum, lithium, sodium-calcium, sodium-aluminum and other metal base greases may be used. The soap may be made from fat, oil or fatty acid.. In addition to common lard or tallow, other suitable fats and oils which may be used are bone fat, castor oil, corn oil, cottonseed oil, horse fat and wool fat. Various fatty acids having from approximately 15 to 24 carbon atoms per mole.- cule, such as oleic acid, stearic acid, animal fatty acids, cottonseed fatty acids, as well as petroleum naphthenic acids and acids obtained from oxidation of paraffin waxes may be used. Whether or not the fatty acid or the fat or oil is used will depend on whether it is desired to have `glycerin present inthe final product. Various additives for imparting particular characteristics to the grease may also be added. Fillers suchA asl graphite, asbestos and sulfur may be blended into the mixture fed to the slurry tanks. Where it is desired to produce a grease with stringiness, high molecular weight poly-isobutylene polymers or natural or synthetic rubber may be added in small amounts. Anti-oxidants such as phenol, naphthylamine, amino` phenols and others may be added in small amounts. Extreme pressure addition agents such as sulfurixed fatty oils, sulfurized and phosphorized fatty oil, sulfochlorinated organic compounds and thio-phosphoric acid organic compounds may be added.

Assuming that slurry tank fsv isA first charged, the slurry is circulated to and from tank 3 and to and from disperser or homogenizer 2l until thesoap and additives are uniformly dispersed in the oil. Circulation to and from the slurry tank should be continued until the entire Volume of material in the slurry tankV has had an opportunity to pass through the homogenizer 2 I. Valve I3A in the line Il is then closed and suspension is withdrawn from tank `ilthrough line 33 by means of. pump 4 3. At the time withdrawal of suspension from line 33. to tank 3 is begun, tank l is filled with the required mixture ofsoap, oil and additive and cyclic circulation of the mixture to and from tank 'l through homogenizer 2| is carried-out until a uniform suspension is obtained and is, continued until tank 3., is substantially empty, at which timel valves 37. and Il are closed and valve 3S` opened to permit withdrawal of Stock from tank 'l by means of pump 43. Tank 3Y is then refilled, valve I3 opened and cyclic circulation begun through the tank and the homogenizer or disperser 2 l. In this manner substantially continuous flow of the ingredients of the grease mixture from the slurry tanks 3- and l can be maintained through the remainder of the apparatuS.

When initially starting the apparatus, it may be preferable to circulate the dispersion from the slurry tank by means of pump 43 through heat exchanger 4E', cooler 5l and back through line 69.

until the heat exchanger and cooler have attained a balanced condition thereby insuring proper heating and cooling of the soap stock during actual processing. During this initial circulating operation, valves 5I, 6I and l5 as Well as the valve in line 64 are closed and valve 5S is opened.

The processing of the grease mixture from the pump 43 through the remainder of the apparatus depends on the nature of the grease. Soaps when subjected to heat, exhibit three transitional temperatures, known as the uni-dimensional, bi-dimensional and tri-dimensional melting points. The loi-dimensional melting point is also known as the plasticity point and the tri-dimensional melting point is also known as the complete melting point. The transitional temperatures depend on the nature of the soap. For example, in the case of sodium stearato, these temperatures are approximately 164 F. for the uni-dimensional melting point; 266 F. for the bi-dimensional melting point; and 374 F. for the tri-dimenrsional melting point. The transition points become correspondingly lower as the unsaturation of the fat, oil or acid employed in making the soap increases. Since the fats, oils or acids used in making soap for the manufacture of grease are essentially mixtures of stearin and olein or of stearic and oleic acid, the transitional points of the soap. will besomewhat lower. than thfae. givenabove for. Sodiumstearata I have discovered that if the soap-oil mixtme is subjected to homogenizing action at] or slightly above itsy loi-dimensional melt vg or plasticity point but below the tri-dimensional melting point of the Soap, a, grease of excellent texture and appearance can be made in a continuous operation.

When preparing sodium soap greases, sodiurn by Weight of water and fromy approximately., 0

to 5% by weight. of glycerin. Where additives are used, the proportions of the aforesaid ingredients Will be accordingly reduced. Themixtureleaves the Votator or other` heat exchanger M in a uniform state of suspension, andY passes through Kombinator or other homogenizer- 5 3y where complete dispersion of the` soap in theoilis obtained and orientation of the soap molecules into a definite pattern or lattice takes place by the extremely high conditions of' shear developed in the homogenizer. The samer. action takes place,v to some extent in conventionalkettle;v

grease operations, but the orientation of the soap molecules is less d enite because of the lower conditions of shear.

From the KombinatororA other homogenizer 5.3` the grease passes to a cooling Votator or othersuitable cooling means 5l' where the telnr. perature of the grease is lowered to a point` between its uni-dimensional andbi-dimensional melting point. Depending on the .particular soap employed, its temperature rwill vary from 4 aboutv to 2Gb" F. inorder to obtain a grease with` a brous texture. During the cooling process, in the Votator or other cooling element, the grease structurev may be. partially brokendown, making the greasey unsatisfactory. for Wheelbearing lubrication and unable to consistently pass the CRC wheel-bearing test. In order to obviate this diiculty, the grease after leaving Votator 51 passes into a third Kombinatoror other homogenizer G3 ata temperature. approxi- 5., mating uni-dimensional melting point of the soap, namely, 150 to 200 F. Passage ofthe grease through the Kombinator or Cornell grease homogenizer at this temperature has the desired effect of restoring the grease to the desired texture.

From the hcmogenizer 63 the grease is taken through line 65 and is at a sufficiently low temperature for packaging.

When it is desired to produce a sodium soap grease having a smooth rather than a fibrous texture, the grease leaving Kombinator or other homogenizer 53 is cooled down to a temperature of 75 to 125 F. in the cooling Votator or other heat exchanger 51, that is, the grease is cooled to a temperature below its uni-dimensional melting point while being subjected to a certain amount of shear in the cooling Votator. Grease prepared in this manner is ready for packaging after it leaves the cooling Votator 51 and does not require further processing in the Kombinator or other homogenizer 63.

When the apparatus is used to prepare calcium soap grease, an amount of water equivalent to approximately -15 by weight based on the weight of soap used, should be present in the mixture in the slurry tank in order to stabilize the lubricating grease. The mixture will contain approximately 1 to 40% of soap, approximately 60 to 99% of oil, and from 0 to 4% of glycerin. These percentages will be reduced accordingly if additives are used.

The suspension is pumped to the heating Votator or other heat exchanger 41 where the temperature is raised to approximately the bidimensional melting point of the calcium soap or somewhat above this point but below the tri-dimensional melting point. The melting points of the calcium soaps are lower than in the case of the sodium soap. WithY respect to calcium soaps, a temperature of approximately 212 to 250 F. will be reached in Votator 41 depending on the specic fat used in preparing the soap. From the heating Votator 41, the mixture passes at the aforesaid temperature to the Kombinator or other homogenizer 53 where the combination of soap, oil and water into grease takes place. From the Kombinator or other homogenizer 53 the grease passes through the cooling Votator 51 where the grease is cooled to a point which experience indicates is best for the particular grade or consistency of grease involved. This temperature is directly proportional to the soap content or consistency of the grease and generally will vary from about 130 F. lfor a zero consistency to approximately 210 F. for a No. 6 consistency. The grease leaving the cooling Votator 51 may be packaged directly through valve-controlled line B4 or may be subjected to further homogenizing in the Kombinator or homogenizer 63 to insure proper texture. If a homogenizer such as a Cornell grease homogenizer is used in this last step, deaeration of the grease is effected.

Where it is desired to manufacture aluminum soap grease, the suspension of aluminum soap and oil is pumped into the Votator or other suitable heat exchanger 51 where it is heated to approximately 275 to 310 F. For the preparation of aluminum soap greases, the mixture charged to the slurry tank will contain approximately 2 to 25% by weight of soap, about 75 to 98% of oil, with these proportions reduced in the event additives are used.

The mixture of soap and oil passes directly from Votator 41 thrugh une 55 tavotator 51' where the temperature is reduced to about 150 F. From' Votator 51 the mixture passes to time lag tank 11 to give the mixture suflicient time for gelation. The time lag tank or unit 11 should be of suflcient size to permitthe mixture to move continuously therethrough. From the time lag tank 11 the mixture is pumped to Kombinator or other homogenizer 53 in order to homogenize the mixture into the finished grease. From the homogenizer 63 the grease leaves through line 65 for packaging.

Where it is desired to prepare mixed soap greases such as sodium-lime, sodium-aluminum, or calcium-aluminum soap greases, the temperatures to be observed in each step will be intermediate to those for the temperatures required with regard tothe individual soaps. Since the sodium soap generally comprises the dominant portion of the soap in mixed sodium soap greases, the processing temperature will generally approach that of the temperature required for preparing sodium soap greases. In general the temperature will approach the temperature required for the soap present in dominant proportions.

. The proportions of the various ingredients such as soap, mineral oil, additives, and water which are used in preparing the soaps in accordance with my process, are the same as those which are generally used in the industry for preparing the various types of soap aforementioned. The type of oil used in preparing the grease is that conventionally used in preparation of greases by common batch method. The oil may be derived from 'parailinic naphthenic or mixed base crude, and may be a residual or distillate fraction suitably rened by acid, clay or solvent treatment. The viscosity of the oil used will, in general, vary between approximately 35-300 seconds Saybolt at 210 F. depending somewhat on the nature of the soap used in the preparation of the grease.

It is to be understood that although I prefer to use a Votator for the heating and cooling steps. any efficient mechanism for continuously heating vor cooling plastic materials, such as greases, may

be used in place thereof. The mixing action obtained in the Votator is immaterial to my Iprocess except insofar as it aids in obtaining ecient heating or cooling of the grease components.

An advantage of my process not heretofore mentioned is that it presents an easyway of getting rid of slop, line-cleanings and various materials which accumulate during grease manufacture. Such materials may be dumped into the slurry tanks and processed along with the oil and soap charged thereto.

It will be seen, therefore, that I have devised apparatus which is capable of continuously or semi-continuously making grease from various types of soap bases and that I have discovered that by heating and cooling the grease components to certain critical temperatures in a definite sequence, greases of excellent properties can be prepared in a continuous operation.

VIt is claimed:

1. The method of preparing sodium soap grease in a continuous operation comprising preparing a slurry of said soap in mineral oil, heating the slurry to a temperature between approximately 220 and 290 F., at which the soap is above its plasticity point but below its true melting point,

homogenizing the slurry while at saidtempera-V ture until it has attained the desired grease structure, and then reducing the temperature of the resulting greasefbelowY thefplastictypont of the soap before packaging.

2. Method in accordance with claim. 1 ira-Which.- the greasev is cooled. to a temperature below the:

uni-dimensional melting point of the soap, namer 1y, 759 to 125 F., after homogenization,.and then? packaged.

3.Y Methodin accordance with claim 1 inwhichl` the grease subsequentI to homogenization-is cooled. to a temperature approximating theuni-dimem sional melting point ofthe soap name1yf,150o to 200 F., and again homogenized at this tempera.- ture prior to cooling and packaging.

i Number l REFERENCES. CITEDv 'I-hefoliowing references are of record in the ie of;4 thi'spa-tent:

UNITED. STATES, PATENTS Name Date 2;3118,668. Calkins May 11, 1943 2;332,202 Calkins Oct. 19, 1943 2,365,037 Zimmer et al. Dec. 12, 1944 2,332,052.A Beerbower et= al Mar. 20, 1945 2,374,913 Beerbower et a1.'v May 1', 1945 2,417,495 Houlton Mar. 18, 1947 

1. THE METHOD OF PREPARING SODIUM SOAP GREASE IN A CONTINUOUS OPERATION COMPRISING PREPARING A SLURRY OF SAID SOAP IN MINERAL OIL, HEATING THE SLURRY TO A TEMPERATURE BETWEEN APPROXIMATELY 220* AND 290* F., AT WHICH THE SOAP IS ABOVE ITS PLASTICITY POINT BUT BELOW ITS TRUE MELTING POINT, HOMOGENIZING THE SLURRY WHILE AT SAID TEMPERATURE UNTIL IT HAS ATTAINED THE DESIRED GREASE STRUCTURE, AND THEN REDUCING THE TEMPERATURE OF THE RESULTING GREASE BELOW THE PLASTICITY POINT OF THE SOAP BEFORE PACKAGING. 